1 files changed, 120 insertions, 0 deletions
diff --git a/ports/rp2/machine_adc.c b/ports/rp2/machine_adc.c
new file mode 100644
index 000000000..f0f367151
--- /dev/null
+++ b/ports/rp2/machine_adc.c
@@ -0,0 +1,120 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2020-2021 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "py/runtime.h"
+#include "py/mphal.h"
+#include "hardware/adc.h"
+
+#define ADC_IS_VALID_GPIO(gpio) ((gpio) >= 26 && (gpio) <= 29)
+#define ADC_CHANNEL_FROM_GPIO(gpio) ((gpio) - 26)
+#define ADC_CHANNEL_TEMPSENSOR (4)
+
+STATIC uint16_t adc_config_and_read_u16(uint32_t channel) {
+    adc_select_input(channel);
+    uint32_t raw = adc_read();
+    const uint32_t bits = 12;
+    // Scale raw reading to 16 bit value using a Taylor expansion (for 8 <= bits <= 16)
+    return raw << (16 - bits) | raw >> (2 * bits - 16);
+}
+
+/******************************************************************************/
+// MicroPython bindings for machine.ADC
+
+const mp_obj_type_t machine_adc_type;
+
+typedef struct _machine_adc_obj_t {
+    mp_obj_base_t base;
+    uint32_t channel;
+} machine_adc_obj_t;
+
+STATIC void machine_adc_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
+    machine_adc_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    mp_printf(print, "<ADC channel=%u>", self->channel);
+}
+
+// ADC(id)
+STATIC mp_obj_t machine_adc_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *all_args) {
+    // Check number of arguments
+    mp_arg_check_num(n_args, n_kw, 1, 1, false);
+
+    mp_obj_t source = all_args[0];
+
+    uint32_t channel;
+    if (mp_obj_is_int(source)) {
+        // Get and validate channel number.
+        channel = mp_obj_get_int(source);
+        if (!((channel >= 0 && channel <= ADC_CHANNEL_TEMPSENSOR) || ADC_IS_VALID_GPIO(channel))) {
+            mp_raise_ValueError(MP_ERROR_TEXT("invalid channel"));
+        }
+
+    } else {
+        // Get GPIO and check it has ADC capabilities.
+        channel = mp_hal_get_pin_obj(source);
+        if (!ADC_IS_VALID_GPIO(channel)) {
+            mp_raise_ValueError(MP_ERROR_TEXT("Pin doesn't have ADC capabilities"));
+        }
+    }
+
+    adc_init();
+
+    if (ADC_IS_VALID_GPIO(channel)) {
+        // Configure the GPIO pin in ADC mode.
+        adc_gpio_init(channel);
+        channel = ADC_CHANNEL_FROM_GPIO(channel);
+    } else if (channel == ADC_CHANNEL_TEMPSENSOR) {
+        // Enable temperature sensor.
+        adc_set_temp_sensor_enabled(1);
+    }
+
+    // Create ADC object.
+    machine_adc_obj_t *o = m_new_obj(machine_adc_obj_t);
+    o->base.type = &machine_adc_type;
+    o->channel = channel;
+
+    return MP_OBJ_FROM_PTR(o);
+}
+
+// read_u16()
+STATIC mp_obj_t machine_adc_read_u16(mp_obj_t self_in) {
+    machine_adc_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    return MP_OBJ_NEW_SMALL_INT(adc_config_and_read_u16(self->channel));
+}
+MP_DEFINE_CONST_FUN_OBJ_1(machine_adc_read_u16_obj, machine_adc_read_u16);
+
+STATIC const mp_rom_map_elem_t machine_adc_locals_dict_table[] = {
+    { MP_ROM_QSTR(MP_QSTR_read_u16), MP_ROM_PTR(&machine_adc_read_u16_obj) },
+
+    { MP_ROM_QSTR(MP_QSTR_CORE_TEMP), MP_ROM_INT(ADC_CHANNEL_TEMPSENSOR) },
+};
+STATIC MP_DEFINE_CONST_DICT(machine_adc_locals_dict, machine_adc_locals_dict_table);
+
+const mp_obj_type_t machine_adc_type = {
+    { &mp_type_type },
+    .name = MP_QSTR_ADC,
+    .print = machine_adc_print,
+    .make_new = machine_adc_make_new,
+    .locals_dict = (mp_obj_dict_t *)&machine_adc_locals_dict,
+};